Fuze mechanisms



3,015,276 FUZE MECHANISMS Benyamm John Surtees, 31 Churchill Ave, Horsham, England ljilerl Sept. 3, 1958, Ser. No. 758,862 Claims priority, application Great Britain Sept. 3, 1957 2 Claims. (Cl. 102-76) This invention relates to striker mechanisms for fuzes and more particularly for fuzes of the impact type and its object is to provide such a mechanism which will remain in a safe condition until a cocking or arming action is applied and which thereafter is capable of being actuated by an impact load applied in any direction.

The invention therefore comprises a striker mechanism for an impact type fuze which mechanism includes a striker member restrained from forward movement by displaceable members, and a plunger rearward of the striker member and which on assembly, is separated therefrom by a substantially unstressed spring, which plunger incorporates a guard to retain the displaceable members in position. This plunger is arranged to move forward under the action of pressure applied rearwardly thereof thereby compressing the spring and moving the guard from its retaining position whereafter the displaceable members may be displaced by any impact load on the mechanism to allow the striker member to move forward under the action of the spring.

The pressure required to produce the forward movement of the plunger necessary to arm the fuze may be derived from any suitable source such as compressed air, a hydraulic system or the firing of an explosive charge. For some purposes, for example, use in conjunction with an anti-personnel or anti-tank mine, the pressure may be applied directly or indirectly by the weight of a person or vehicle passing over the mine. For other purposes it may be suitable to apply direct pressure by hand or through a thrust rod to the plunger to arm the fuze.

One form of striker mechanism in accordance with the invention will now be more particularly described, by way of example only, with reference to the accompanying drawings in which:

FIGURE 1 is a longitudinal section of the mechanism in its safe position,

FIGURE 2 is a transverse section at 11-11 of FIG- URE 1,

FIGURE 3 is a longitudinal section of the mechanism in its armed position and FIGURE 4 is a longitudinal section of the mechanism in its operative or firing position.

The mechanism is contained in a casing 1 whose external surface may have any suitable transverse section (here shown substantially square) and whose internal form is cylindrical, the rear part being counterbored to a slightly larger diameter to form a rearwardly facing shoulder 2 at an intermediate point of its length. Within the casing is a striker housing comprising a plunger 3, a base member 4 and three guard tongues 5 carried by and extending forwardly of the plunger. The plunger 3 is cylindrical and of such diameter that it can slide within the forward part of the casing 1, the forward movement being limited by a circumferential flange 6 at the rear end of the plunger 3 which flange extends into the counterbore of the casing 1 rearward of the shoulder 2. The base member 4 has a forward cylindrical portion of reduced diameter which is located in a recess in the rear end of the plunger 3 and is retained by screws 7. The rear end of the base member 4 has a rearwardly extending peripheral flange 8. The guard tongues 5 which may be attached to or integral with the plunger 3 extend first forwardly and then radially inward from the periphery of the plunger 3 and each has a cir- "ice cular hole 9 through its radial portion. The three guard tongues 5 are equispaced around the plunger 3. The base member 4 may, if desired, be formed integrally with the plunger 3.

A striker member comprising a transverse member such as a plate or (as shown) a spider having a rearwardly extending central boss 10, three radial arms 11 and a forwardly directed striker pin 12. This striker member is located so that each arm 11 rests behind the radial portion of one of the guard tongues 5. A spiral spring 13 is located between the striker member and the striker housing and lies partly within an axial hole 22 in the plunger 3 and partly extends about the boss 10.

The rear end of the casing 1 is closed by a screw plug 14 having therein a threaded axial orifice 15. Forward of the plug 14 is a ring 16 whose outer surface is in contact with the inner surface of the counterbore of the casing 1. The ring 16 may be a separate unit fitting tightly within the counterbore of the casing 1 or may be made integral with a plug 14.

In the safe position as shown in FIGURE 1 the striker housing is in its most rearward position the flange 8 of the base member 4 being in contact with the plug 14 and lying within the ring 16 there being a gap between the shoulder 2 of the casing 1 and the flange 6 of the plunger 3. The arms 11 of the striker member are in contact with the radial portions of the guard tongues 5 and the spring 13 is uncompressed or only lightly compressed. Three small balls 17 rest on the arms 11 of the striker member within the holes 9 in the guard tongues 5 the forward parts of the surfaces of the balls 17 making contact with the ends of three studs 18 carried by the forward end of the casing 1 in axial alignment with the holes 9. The forward end of the firing pin lies Within the rearward end of a guide bush 19 inserted into an axial orifice in the forward end wall of the casing 1. In this position, forward motion of the striker member is prevented by the balls 17 which are retained between the arms 11 of the striker member and the studs 18 by the surrounding guard tongues 5.

The mechanism is armed by pressure applied to the rear face of the base member 4 of the striker housing which pressure may be applied by compressed air, by expanding gases from an explosive charge or hydraulically, the actuating fluid being admitted to the casing 1 through the orifice 15 which is threaded to receive a suitable connector for a supply channel, or the pressure may be applied mechanically. The applied pressure moves the striker housing forward to the position shown in FIGURE 3 where it is retained by the flange 8 which expands into the counterbore of the casing forward of the ring 16. Expansion of the flange 8 may be brought about by radial pressure of the actuating fluid or may be the result of elastic recovery from radial compression applied by the ring 16. The forward movement of the striker housing closes the gap between the flange 6 on the plunger 3 and the shoulder 2 on the casing 1 and carries the guard tongues 5 forward to release the balls 17 from lateral restraint. The balls however are still held in their same restraining positions but solely by pressure exerted by the arms 11 of the striker member which is urged forward by the spring 13 now compressed by the forward movement of the striker housing.

An impact load in any direction will usually be sufficient to dislodge the balls 17 from their unstable position as shown in FIGURE 3 whereupon the balls fall rearward of the arms 11 of the striker member which is urged forward by the spring 13 until the striker pin 12 emerges from the forward end of the casing where it may be arranged to fire a suitable cap to initiate detonation of an explosive charge.

The studs 18 may be fixed into the end wall of the casing 1 or may fit loosely therein and be retained longitudinally by other parts of the fuze or other store in connection with which the mechanism is to be used. Rotation of the striker housing may be restrained by any suitable means such as a stud 20 inserted in the casing 1 and extending therethrough into a longitudinal groove 21 in the outer surface of the plunger 3 and one of the guard tongues 5.

If desired the upper faces of the arms 11 of the striker member may be provided with slight indentations or longitudinal grooves with which the balls may engage. Such indentations or grooves may impart a slight restraint to displacement of the balls after arming but the restraint may be made sufiiciently small to ensure that the mechanisms will operate when subjected to an appropriate impact load.

It will be readily appreciated that, although three balls are used in the mechanism described, the displaceable elements may be of any other suitable shape and any suitable number may be used in conjunction with a corresponding number of radial arms on the striker member and a corresponding number of guard tongues.

The mechanism may be manufactured wholly or in part from non metallic and/ or non magnetic materials to render its location by detecting devices more difficult. For example, the striker pin 12, the balls 17, the spring 13 and the screws 7 may be of metal, the remainder of the mechanism being made of a material such as those known under the general term plastic. The base member 4 may, if desired, be made of a flexible material such as polyethylene.

The base member 4 may if desired be made integral with the plunger 3, but the two part construction described allows the use of a different more flexible material for the base member 4.

I claim:

1. A striker mechanism for an impact type of fuze, comprising a casing having openings in the top and bottom thereof, a plunger slidable within said casing, symmetrically disposed tongues attached to the plunger projecting upwardly and bent radially inward, each tongue being provided with an opening in the bent portion near its end, balls disposed within each opening and free to move therethrough, a striker member having a firing pin and located interiorly of said symmetrically disposed tongues and resiliently connected to said plunger, radial arms extending from the striker member contiguous with each tongue while said striker mechanism is in safe position, said radial arms contacting the tongues to close each opening and retain the balls therein, fixed studs protruding interiorly of said casing and aligned with the respective openings of the tongues to contact and maintain the balls in a fixed position and the striker member in a safety position, pressure fluid means from a high pressure source introduced through the bottom opening of the casing to move the plunger and the tongues attached thereto upwardly away from said balls to remove the safety on the striker member, said balls held axially by the studs to maintain the striker member in an armed position and free to move laterally on impact to release the firing pin of the striker member through the top opening of the casing.

2. A striker mechanism for an impact type of fuze comprising a casing having openings in the top and bottom thereof, a plunger slidable within said casing, symmetrically disposed tongues attached to the plunger projecting upwardly and bent radially inward, each tongue being provided with an opening in the bent portion near its end, balls disposed within each opening and free to move therethrough, a striker member having a firing pin and being axially movable between said tongues and connected by resilient means to the plunger, radial arms extending from the striker member contiguous respectively to each tongue, said radial arms contacting the tongues to close each opening and retain each ball therein, fixed studs protruding interiorly of said casing and aligned with each respective opening in each of the tongues to maintain the balls in a fixed position and the striker member in a safety position, said resilient means comprising a spring interposed between the striker member and the plunger, pressure fluid means from a high pressure source introduced through the bottom opening of the casing to move the plunger and further compress the spring bearing on the striker member, said tongues actuated by the movement of the plunger to slide on the studs and remove the lateral restriction on the balls to arm the fuze, said balls being axially held by the studs to maintain the striker member in an armed position and free to move laterally on impact to release the firing pin of the striker member through the top opening of the casing.

References Cited in the file of this patent UNITED STATES PATENTS 682,728 Lynch Sept. 17, 1901 2,145,507 Denoix Jan. 31, 1939 2,243,621 Denoix May 27, 1941 2,730,046 Bergstrom Jan. 10, 1956 2,779,286 Marshall Jan. 29, 1957 2,872,868 Donahue Feb. 10, 1959 2,872,869 Rasmussen Feb. 10, 1959 2,873,681 Lauritsen Feb. 17, 1959 2,883,933 King Apr. 28, 1959 

